Rotation sensing device



Oct. 29, 1963 J. BOCHAN 3,109,076

ROTATION SENSING DEVICE Filed Nov. 25, 1960 2 Sheets-Sheet l PIC-3.!

INVENTOR. I OH N BOCHAN BYw/OM HIS ATTORNEY Oct. 29, 1963 J. BOCHAN 3,109,076

ROTATION SENSING DEVICE Filed Nov. 25, 1960 2 Sheets-Sheet 2 FICZZ 7| FIG.4

M INVENTOR.

Si J'OHN BOCHAN wffw HIS ATTORNEY United States Patent 3,109,076 ROTATION SENSING DEVICE John Bochan, Louisville, Ky., assignor to General Electric Company, a corporation of New York Filed Nov. 25, 1960, Ser. No. 71,671 2 Claims. (Cl. 200-32) This invention relates to devices for Sensing rotation of a machine part, and more particularly to devices for providing inherent protection to the machine in response to a failure of the machine part to rotate.

To prevent machine damage, it is often important that, if the machinery should cease to rotate for any reason whatsoever, various other functions of the machine also be intermpted. Typical of such instances is the case of the domestic clothes dryer; such machines provide a heat drying operation to effect complete drying of clothes after they have been washed, either in a separate machine or in the same machine as in the case of combination washer dryers. The heat drying operation is usually provided by heating elements which are positioned so that the heat from them is transmitted to the clothes. If for any reason the rotation of the basket should stop the clothes will, of course, merely lie at the bottom of the basket. In such a case, the heat from the heating elements, if they are allowed to remain energized, may cause a localized temperature rise within the dryer to an extent where the clothes may become scorched or parts of the machine may be damaged. For these reasons, it is highly desirable that energization of the heating elements be terminted as soon as rotation of the basket ceases for any reason whatsoever; to efiiect this result, suitable rotation sensing means for thebasltet need to be provided. Because of the consequences which can result from malfunctioning of such rotation sensing devices, it is important that they be of simple construction, reliable under virtually all circumstances, yet economical enough to be incorporated in mass production devices without causing a substantial increase in the cost of such devices.

It is therefore an object of the present invention to provide an improved rotation sensing device.

A further object of the invention is to provide sue a device in which a pumping efiect provided by rotation of a member keeps a switch closed, and the switch is permitted to open when the pumping stops, that is, when the member stops rotating.

In accordance with my invention, I provide a device for sensing the rotation of a member having an annular surface with at least one rise formed thereon. The rotation sensing device has a movable member biased against the annular surface, and the movable member in turn operates pumping means during rotation. The pumping means communicates with a chamber which has a Wall portion deformable in response to pressure in the chamber, the pumping means thus being effective during its operation to raise the fluid pressure within the chamber. The wall portion controls switch means which has first and second positions; the switch means is moved to the first position when the wall portion deforms, and. to its second position when the pressure in the chamber is too low to deform the wall portion. In addition, I provide a leakage path from the chamber so that as soon as pumping is stopped the pressure in the chamber decreases. In this manner, when rotation ceases, the pressure in the chamber decreases and as a result the switch means moves from its first position to its second position.

The subject matter which I regard as my invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. The invention itself, however, may best be understood by reference to 3,lli9,0 76 Patented Oct. 29, 1963 the following description taken in conjunction with the accompanying drawings.

In the drawings,

FIGURE 1 is a side elevational view of a clothes drying machine which incorporates my improved rotation sensing devices;

FIGURE 2 is a View along line 2-2 in FIGURE 1;

FIGURE 3 is a view along line 3-3 in FIGURE 2; and

FIGURE 4 is a schematic diagram showing in simplified form an appropirate electrical circuit in which my rotation sensing device may be used for safety purposes.

Referring now to FIGURE 1, I have shown therein a domestic clothes dryer 1; a clothes tumbling receptacle or drum 2 is provided within a suitable outer casing or cabinet 3 which completely encloses it on all sides. The drum is mounted for rotation within the cabinet on a substantially horizontal axis, and is generally cylindrical in shape, having a first central outer wall portion 4, second and third outer wall portions 5 and 6 located respectively adjacent the ends of the drum, a back wall 7 and a front wall 8. Outer wall sections 4, 5 and 6 are imperforate over their entire length so that the entire outer shell of the drum 2 is imperforate; on the interior surface of central portion 4 there is provided a plurality of clothes tumbling ribs 9.

The front of drum 2 is rotatably supported on the outer casing by means of a pair of idler rollers, one of which is shown by the numeral Ill, which are rotatably secured to the top of an upwardly extending member 11 fastened as its bottom to the base 12. The rollers Iii are disposed beneath the drum in contact with portion 6 thereof so that the drum is supported on the rollers at its front end and is free to rotate. The rear end of drum 2 receives its support from a roller wheel 13 which is positioned beneath portion 5 of the drum in supporting and frictionally driving engagement therewith.

Roller 13 is mounted on a shaft 14 supported in bearings I5. At one end of shaft 14 there is secured a pulley 16 driven from a belt 17 in turn powered by a pulley 18 mounted on the end of shaft 19 of an electric motor 29. The motor, pulleys, and roller 13 are so proportioned to the drum and to each other that drum 2 is rotated by roller 13 at an appropriate relatively low speed to provide tumbling action for articles of clothing placed therein. With the driving arrangement described, the driving roller 13 provides the entire support for the rear end of drum 2 so that the force with which the drum presses down on it is a direct reflection of the weight of the clothes in the basket.

In order that a stream of drying air may be introduced to and passed through the clothes drum, the drum is provided with a central aperture 21 in its front wall 8 and with a plurality of perforations 22' extending in an annulus around its back wall 7. Rig-idly secured to the rear wall 23 of cabinet 3 by any, desired means such as, for instance, welding at suitable points 24, is a battleshaped member 25 which has secured thereto heating elements 26 appropriately insulated from the bafie member. Heating elements 26 may be annular in shape so as to be generally coextensive with perforations 22 in drum 2. A second baffle member 27 is rigidly secured to the back wall 7 of the drum outside the ring of perforations 22. and within the stationary baffle 25 so that an annular air inlet 28 is in eifect formed by the two bafiles 25 and 27. Baffle 27 is further provided with an annular series of openings 29. In this manner, the baffies form inlet duct means, and a passage is provided for air to enter annular inlet 23 between the baffles, pass over the heating elements 26 thereby to be warmed, through openings 29, and then through perforations 22 into the interior of drum member 2.

In order to secure drum 2 so that it is supported by the roller members lti'and 13 without any undue horizontal motion but with a reasonably limited and permissible amount of vertical motion, a suitable thrust bearing arrangement, such as that generally indicated at 29a is provided in baffle member 25 to receive a stub shaft 291) secured to baffle member 27. Thebearing arrangement 29a permits the entire weight of the drum 2 and its contents to be taken up by the roller member 13 while at the same time preventing any tendency toward displacement of the drum in any horizontal direction. The construction including bearing arrangement 29a is described in .full detail and is claimed in application Serial No. 789,869, filed January 29, 1959 by William L. Simpson (now Patent 3,009,259 issued November 2-1, 1961) and assigned to General Electric Company, assignee of the present invention.

The front opening 21 of the drum is substantially closed by means of a stationary bulkhead generally indicated by the numeral 30. Bulkhead 30' is made up of a number of adjacent members including the inner surface 31 of an access door 32 mounted on the dryer cabinet, a stationary frame 33 for the door, the inner surface 34 of an exhaust duct 35 leading from the drum, and an annular flange 36 mounted on the frame 33 and the duct wall. It will be noted that a suitable clearance is provided between the inner edge of the drum opening 21 and the edge of bulkhead 3%) so that there is no rubbing between the drum and the bulkhead during rotation of the drum. In order to prevent any substantial air leakage through opening 21 between the interior and exterior of the drum a suitable ring seal 37, preferably formed of felt-like material, is secured to flange 36 in sealing relationship with the exterior surface of drum wall 8.

Front opening 21 serves both as part of the air flow path through the drum and as a means whereby clothes may be loaded into and unloaded from the drum. The door 32, whose inner surface forms part of the bulkhead 30 closing the opening 21, is mounted on cabinet 3 and when the door is opened clothes may be inserted'into or removed from the drum through the door frame 33. It will be noted that the door includes an outer imperforate section 38 and an inwardly extending hollow section 39 mounted on the fiat outer section. Hollow section 39 extends into the door frame 33 when the door is closed, andJ-the door surface 31 which comprises a part of the combination bulkhead 30 is actually the inner wall of this hollow section. The air outlet from the basket is provided by a perforated opening 40 formed in the inner wall 31 of hollow door section 39. The bottom Wall of the door section 39 and the adjacent wall of door frame 33 are provided with aligned openings 41 and 42, with opening 42 providing the air entrance to duct 35. Suspended from opening 42 may be provided a lint trap 43 of any suitable porous material which permits the air to pass therethrough into the duct 35 but which retains lint for later removal. The duct 35 leads to a centrifugal blower 44 which is mounted on the motor shaft and thus directly driven by motor 29*. Blower 44 is formed in the conventional manner (not further shown) to be connected through an exhaust duct with an outlet from the cabinet 3.

When motor 20 operates, roller 13 is rotated through the pulleys 18 and belt 17 in order to effect rotation of drum 2 so as to tumble the clothes. Also blower 44 is operated so as to pull air into the cabinet through suitable ducts (not shown), through openings 28, over heaters 26, through openings 29 and perforations 22, then through the drum and into the door opening 40, then through openings 41 and 42 and the lint trap 43, and through the duct 35 to the blower 44 which then forces the moist air out of the machine; In addition, the heaters 26 are energized so as to cause the air thus being passed over the clothes to be warmed. The hot air thus contacting the clothes causes exaporation of moisture from the clothes, thereby drying them.

In order to control the sequence of operations, and cause termination of the operation at a suitable time, an appropriate control mechanism 45 (shown schematically in FIGURE 4) may be provided and may be positioned within the backsplasher 46 formed above the cabinet 3 as shown in FIGURE 1. Referring now more particularly to the simplified and schematic control diagram of FIGURE 4, a suitable source of power (not shown) may be connected through the control mechanism 45. This may be effected, in the usual fasion, by a three-wire system wherein a pair of conductors 47 and 48 each are provided at a potential difference of 110 volts from a neutral conductor 49, the potential difference between the conductors 47 and 48 being 220 volts.

Within the control mechanism 45, suitable switching means (not shown) may be provided for controlling the operation of the heaters 26 in FIGURE 4 and of the driving motor 26, schematically shown as including a main winding 5! and a start winding 51 in parallel therewith. It will be understood that the switching means contained within the control mechanism 45 cause, in the usual manner, operation of motor 20 throughout a drying cycle and operation of the heating elements 26 at appropriate times.

The motor 20 may be provided with a centrifugal mechanism 52 which controls a switch 54 arranged so that when closed it connects windings Sit and 51 in parallel with each other and in series with a pushbutton start mechanism 55. Switch 54 is in the position shown when motor 20 is stopped; thus, when the control 45 is conditioned for operation and the pushbu-tton 55 is depressed, the motor 20 will be caused to start by the two windings in parallel. As the motor comes up to speed, switch 54 is moved by mechanism 52 into engagement with a contact 56. This disconnects the start winding 51 from the circuit, and connects winding 56 for energization through a conductor 57. Thus, when the manual pushbutton start switch 55 is released, motor 20 will continue to operate on its main winding 59 through conductor 57.

It will be recognized that, should for any reason there cease to be rotation of the drum 2 during the energization of heaters 26, undesirable results may occur. This may come about as the result of motor failure, in which case the drum would cease to rotate and the blower 44 would cease to pull air through the drum, or as the result of slippage of belt 17 due to wear, or the like' It is therefore important in commercially produced machines to provide some means for positively preventing operation of the heaters should the drum fail to rotate for. any reason. In order to cause opening of the heater energizing circuit whenever rotation of drum 2 ceases, I provide a switch 58, connected in series with the heaters, as a part of an improved rotation sensing device 59 secured to baflle 25 as illustrated in FIGURE 1.

Referring to FIGURES 1 and 2 together, it will be observed that my rotation sensing device includes a member 60 positioned with one end 61 in engagement with portion 62 of wall 7. As will readily be observed from FIGURE 1, portion 62 is an annular segment extending entirely around the back wall 7 of the basket. In at least one location around the annular wall segment 62, there is provided a rise 63, shown in FIGURE 2 at the instant it is adjacent the member 60* so that continued rotation of the drum will cause engagement of end 61 of member 60 with the rise 63.

The opposite, or remote, end 64 of member 60 engages the dished. central portion 65 of a part 66 of a piston assembly 66a. Piston assembly 66a also includes a part 67, and a rubber O-ring 63 is positioned between parts 66 and 67, the space between the parts being somewhat greater than the width of the O-ring.

Part 67 also forms a seat for a spring 69 which is seated at its other end against a plate member 70 rigidly secured within housing 71. Housing 71, in addition, has a portion 72 forming a cylinder 72a within which the piston 66a reciprocates, portion 72 then merging into a portion 73 which forms a guide for the reciprocating movement of member 60.

This reciprocating movement is caused by rotation of the drum 2: once each revolution the rise 63 pushes the member 64] to the left, as seen in FIGURE 2, against the action of spring 69, the spring then pushing the member 60 back as soon as the rise passes. Due to the seating of end 64 of member 60 in dished section 65 of the piston 66a, reciprocating movement of member 60 is transmitted to piston 66a, so that during rotation of the drum 2 piston 66:: is reciprocated in the cylinder 72a.

One or more openings 74 are provided in part 67 of the piston 66a. Also, both parts 66 and 67 fit quite loosely in casing part 72 so that there is a substantial fluid path provided around them in cylinder 72a. O-ring 68, on the other hand, stays in sealing engagement with casing 72 during its movement in the cylinder. During reciprocation of piston 66a, movement of the piston to the left results in the O-ring 68 being jammed against the portion 66 of the piston. This seals any outlet for air therefrom and prevents air from escaping. In this manner, movement to the left of the piston constitutes a compression stroke on any fluid, such as air, which is in the cylinder.

When the piston moves back to the right under the influence of spring 6%, part 67 engages the O-ring 68 which is then separated from part 66. There is then a free air passage around the end of part 66 through the space between part 66 and the O-ring, and then through opening 74, the cooperation of O-ring 68 with parts 66 and 67 providing, in effect, a one-Way valve permitting fluid flow into the cylinder. When the piston 66a moves to the right, it will be seen that is is expanding the volume within the cylinder 72a. Thus movement to the right of the piston constitutes a suction stroke, during which suitable fluid, preferably air in the particular embodiment disclosed, may be sucked in through the valve means formed by the O-ring 68 alternatively engageable with member 66 or member 67, and the openings 74.

The structure described thus far constitutes pumping means responsive to rotation of drum 2 to compress fluid in the cylinder 72a. The plate 70 forms, in effect, the base of cylinder 72., and is provided with a centrally located opening 75 through which the cylinder communicates with a chamber 76 formed by a hollow flexible member 77 which has one wall 78 rigidly secured against plate 70 and the opposing wall 79 mounted for movement. Wall 79 may be strengthened by a suitable rigid member 80 so that, in response to an increase of pressure within the chamber '76, deflection of member 77 will take place at the portions 81 thereof which join walls 78 and 79. In this manner, an increase in pressure within the chamber causes movement of wall 79 to the left, and a decrease in the pressure within that chamber causes a movement of the wall 7 9 to the right.

Communication between chamber 76 and cylinder 72a is controlled by a one-way check valve structure 82 which is shown in detail in FIGURE 3. Viewing FIG- URES 2 and 3 together, the check valve is in the form of a flap 83 cut out of wall 78. When the pressure within chamber 76 exceeds that within cylinder 72a, the flap is forced against opening 75 in member 70 so as to seal off any communication to the cylinder. However, when the pressure within cylinder 72a exceeds that within chamber 76, the flap is pushed back by the fluid pressure to permit free communication between the chamber and the cylinder. Thus, during compression strokes of piston 66a the increased pressure is transferred to the chamber 76 but during suction strokes of the piston the valve 83 precludes a like drop in pressure in the chamber 76.

When wall 79 of member 77 is moved to the left, as viewed in FIGURE 2, it pushes in a button 84 normally biased to the position shown, to close the switch 58 previously described in connection with FIGURE 4-. When, however, the pressure within chamber 76 decreases to the point where the wall 79 moves back to the right, the button 84-, being biased outwardly, returns to the position as shown in which the switch 58 is open.

The member 77 is provided with at least one very small bleed opening 85 through which the fiuid in the chamber 76 escapes. While as shown this opening may be simply in the form of one or more small holes, it is a known equivalent to pass a thread of some fiber such as cotton through the wall of the member 77, the thread acting as a small controlled-dimension orifice. The space $6 between portion 87 of the housing to which switch 58 is secured and the member 77 may be put in free communication with the atmosphere through any suitable means such as, for instance, openings 88 formed therein. Thus, when there is no reciprocating of the piston 66a in cylinder 72a, pressure within chamber 76 decreases at a rate controlled by the dimensions of bleed opening 85.

In operation then, during rotation of the drum 2, the member 66 is moved back and forth by the rise 63 formed on annular wall portion 62 and this has the aforedescribed pumping effect so as to raise the pressure within chamber 76 and depress button 34 to close switch 58. This keeps the heaters 26 energized under the control of the system 45'. However, should there be a failure of the dryer in which the basket ceases to rotate but the heaters remain energized, the fluid will leak at a controlled rate out through opening 85 and thereby permit return of the button 84 to the position shown so that switch 53 opens. It has been found that small openings of a suitable size to permit opening of the switch in five to ten seconds may readily be provided.

Thus, as long as the drum is rotating there will be a pumping action, and this will keep the heater circuit energized or energizable under the control of system 45. If, however, there is no more rotation, leakage will occur at a rate suitable to open the switch 58 in a very short period of time to insure deenergization of the heaters.

The structure of FIGURE 2 represents the preferred embodiment of my invention in that it provides, in alignment, a reciprocable actuating member 60, a reciprocable piston 66a within cylinder 72a, a chamber 76 with a movable wall 79, and a switch 58 having a movable button 84, all parts of the pumping apparatus being contained within casing 71 and with the same unitary casing in effect enclosing both the pumping apparatus and the switch. This is a compact arrangement which may be economically manufactured and readily provided in small spaces. It will, however, be recognized that while I have used the simplest approach of a reciprocating member 63 operated by a single rise 63 in order to effect pumping, other means, including any desired number of rises, may be provided, the essential point being that the pumping action be directly caused by the rotation of the drum as a result of the provision of the rise 63. For instance, the same structure could fill the functions of cylinder and chamber, with the outlet valve and the leakage path also being combined.

It is a further point, of course, that the present embodiment utilizes air for the fluid operated on by the pumping means since this is obviously the cheapest and most readily available fluid for the purpose. However, it will readily occur that a closed system may be provided, in which the leakage is provided into a reservoir from which the fluid is then taken by the pumping means. It will further be apparent that while a compressible fluid of the gaseous type is preferable, non-compressible fluids such as liquids may be used by small design modifications of the system. It will further be seen that, while an annular surface which, in efiect, 'is perpendicular to the axis of rotation, has been provided with a rise, an annular surface coaxial with the axis of rotation (such as, for instance, outer wall 4) may be provided with the same structural features to perform the same purpose.

Further, while the structure is provided in a particular machine for protective purposes, it will be clear that it may be used for rotation sensing in any other application desired. Thus, While in accordance with the patent statutes I have described what at present is considered to be the preferred embodiment of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and I therefore aim in the appended claims -to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is: i

1. A rotatable member having an annular surface with at least one rise formed thereon; a rotation sensing device comprising a reciprocable member engagingsaid surface and reciprocated thereby upon rotation; a piston positioned at the end of said reciprocable member remote from said rotatable member; a cylinder formed about said piston, said cylinder having its base remote from said rotatable member; a spring positioned within said cylinder biasing said piston toward said rotatable member; a first one-Way valve adjacent said cylinder base permitting fluid flow out of said cylinder during a compression stroke of said piston; a second one-way valve formed between said piston and said cylinder providing communication between said cylinder and atmosphere and permitting flow of air into said cylinder during a suction stroke of said piston; a chamber aligned with said cylinder on the side thereof remote from said rotatable member and communicating with said cylinder through said first valve, said chamber having a wall portion on the side thereof remote from said rotatable member which is movable away from said rotatable member from a first position to a second position in response to an increased pressure in said chamber, said piston during reciprocation thereof raising the pressure of the air within said chamber and thereby. moving said wall portion to its second position away from said rotatable member; switch means controlled by said-wall portion and positioned on the side of said chamber remote from said rotatable member, said switch means including a button member extending therefrom against said wall portion, said switch means having a first position when said button is in its extended position and having a second position when said button is depressed by movement of said wall portion to its second position; and means forming a leakage path from said chamber to atmosphere whereby stopping of rotation results in a decrease in pressure in said chamher and a resultant movement of said button to its extended position. 7

2. For use with a rotatable member having an annular surface with at least one rise formed thereon: a rotation sensing device comprising a reciprocating movable member adapted to engage said surface; means biasing said movable member and adapted to position said movable member against said surface; reciprocating pumping means connected to said movable member so as to be operated by movement of said movable member in response to rotation of said rotatable member; a chamber communicating with said pumping means and having a wall portion movable from a first to a second position in response to increased pressure in said chamber, said pumping means having an inlet formed in communication with atmosphere and during operation thereof raising the air pressure within said chamber; switch means controlled by said wall portion, said wall portion in its first and sec- 0nd positions moving said switch means to its first and second positions respectively; and means forming a leakage path to atmosphere from said chamber whereby stopping of said rotatable member results in a decrease in pressure in said chamber and the resultant movement of said switch means back to its first position.

References Cited in the file of this patent UNITED STATES PATENTS 2,538,038 Ponstingl et a1 Jan. 16, 1951 2,670,444 Schneider Feb. 23, 1954 2,790,597 Turpin Apr. 30, 1957 2,940,674 Hanje et a1. June 14, 1960 3,029,324 Coufler et al Apr. 10, 1962 3,042,767 Grostik July 3, 1962 

2. FOR USE WITH A ROTATABLE MEMBER HAVING AN ANNULAR SURFACE WITH AT LEAST ONE RISE FORMED THEREON: A ROTATION SENSING DEVICE COMPRISING A RECIPROCATING MOVABLE MEMBER ADAPTED TO ENGAGE SAID SURFACE; MEANS BIASING SAID MOVABLE MEMBER AND ADAPTED TO POSITION SAID MOVABLE MEMBER AGAINST SAID SURFACE; RECIPROCATING PUMPING MEANS CONNECTED TO SAID MOVABLE MEMBER SO AS TO BE OPERATED BY MOVEMENT OF SAID MOVABLE MEMBER IN RESPONSE TO ROTATION OF SAID ROTATABLE MEMBER; A CHAMBER COMMUNICATING WITH SAID PUMPING MEANS AND HAVING A WALL PORTION MOVABLE FROM A FIRST TO A SECOND POSITION IN RESPONSE TO INCREASED PRESSURE IN SAID CHAMBER, SAID PUMPING MEANS HAVING AN INLET FORMED IN COMMUNICATION WITH ATMOSPHERE AND DURING OPERATION THEREOF RAISING THE AIR PRESSURE WITHIN SAID CHAMBER; SWITCH MEANS CONTROLLED BY SAID WALL PORTION, SAID WALL PORTION IN ITS FIRST AND SEC- 